Glucoamylase from Monascus rubiginosus has been found to exist in multiple forms on PAGE pattern (E1 through E5), in which E3 and E4 were the two major forms. The precise structure of carbohydrate components, as well as protein sequence content, should be analyzed in order to gain an appreciation of its structure/function relation. The key method for this purpose involves as follows: a. The sample (glucoamylase) is digested with enzyme (PNGaseF, Endo-H and O-glycanase) to release the O/N-linked oligosaccharides; b. The digested samples run on SDS-PAGE gel to analyze the variation of molecular weight and then samples should be analyzed by LC/ESMS to identify sugar fragments. If glucoamylase contains N-linked oligosaccharides, other instruments (MS50, MS/MS) are necessary to dissect carbohydrate structure and protein sequence in detail. All of this work will be done in the UCSF Mass Spectrometry Facility.